钟祥地震台面波震级测定     

赵瑞  李俊超  万禹  刘迁  宋俊朋  兰天 《地震地磁观测与研究》2017,38(4):49-52

整理钟祥地震台2012年至2016年6月全球M_S≥6地震目录,与中国地震台网中心发布的面波震级进行对比分析,统计发现,该地震台面波震级误差主要集中在-1.0—+0.5,为此分析误差存在的原因,并根据实际情况给出解决办法。  相似文献   

东海八角亭海洋深井台地震监测     

宋秀青  孙冬军  朱元清 《地震地磁观测与研究》2017,38(3):159-163

上海市地震局设计、建设的中国第1个真正意义上的海洋深井地震观测台位于东海石油平台上,井深780 m,安装2套JDF-1型地震计进行观测。通过对陆域地震台站记录的大地震进行分析比较、方位校准,采用单台地震分析方法,确定2009年5月—2011年6月记录到的136个地震参数,总结海域地震波形特征。结果表明,该海域地震活动性特征与当地地质构造一致。  相似文献   

The petrogenesis and implications of deformed late Caledonian–early Hercynian granites in the Wuyi area,South China          下载免费PDF全文

Xilin Zhao  Yang Jiang  Guangfu Xing  Minggang Yu  Kai Liu  Zhihong Chen  Shengyao Yu 《Island Arc》2017,26(5)

Precambrian basement rocks have been affected by Caledonian thermal metamorphism. Caledonian‐aged zircon grains from Precambrian basement rocks may have resulted from thermal metamorphism. However, Hercynian ages are rarely recorded. Zircon U–Pb Sensitive High Resolution Ion Microprobe (SHRIMP) dating reveals that zircon ages from the Huyan, Lingdou, and Pengkou granitic plutons can be divided into two groups: one group with ages of 398.9 ±5.3 Ma, 399 ±5 Ma, and 410.2 ±5.4 Ma; and a second group with ages of 354 ±11 Ma, 364.6 ±6.7 Ma, and 368 ±14 Ma. The group of zircon U–Pb ages dated at 410–400 Ma represent Caledonian magmatism, whereas the 368–354 Ma ages represent the age of deformation, which produced gneissosity. The three plutons share geochemical characteristics with S‐type granites and belong to the high‐K calc‐alkaline series of peraluminous rocks. They have (⁸⁷Sr/⁸⁶Sr)_i ratios of 0.710 45–0.724 68 and εNd(t) values of ?7.33 to ?10.74, with two‐stage Nd model ages (T_DM2) ranging from 1.84 Ga to 2.10 Ga. Magmatic zircon εHf(t) values range from ?3.79 to ?8.44, and have T_DMC ages of 1.65–1.93 Ga. The data suggest that these granites formed by partial melting of Paleoproterozoic to Mesoproterozoic continental crust. A collision occurred between the Wuyi and Minyue microcontinents within the Cathaysia Block and formed S‐type granite in the southwest Fujian province. The ca 360 Ma zircon U–Pb ages can represent a newly recognized period of deformation which coincided with the formation of the unified Cathaysia Block.  相似文献   

A 4D variational assimilation scheme with partition method for nearshore wave models     

Qingyang Song  Roberto Mayerle 《Ocean Dynamics》2017,67(8):989-1002

This paper summarizes the development steps of a 4D variational assimilation scheme for nearshore wave models. A partition method is applied for adjusting both wave boundary conditions and wind fields. Nonstationary conditions are assimilated by providing defined correlations of model inputs in time. The scheme is implemented into the SWAN model. Twin experiments covering both stationary and nonstationary wave conditions are carried out to assess the adequacy of the proposed scheme. Stationary experiments are carried out considering separately windsea, swells, and mixed sea. Cost functions decline to less than 5% and RMS spectrum errors are reduced to less than 10%. The nonstationary experiment covers 1 day simulation under mixed wave conditions with assimilation windows of 3 h. RMS spectrum errors are reduced to less than 10% after 30 iterations in most assimilation windows. The results show that for spacially uniform model inputs, model accuracy is improved notably by the assimilation scheme throughout the computational domain. It is found that under wave conditions in which observed spectra can be well classified, the assimilation scheme is able to improve model results significantly.  相似文献   

Analysis of elastic anisotropy of tight sandstone and the influential factors     

Lian-Teng Song  Zhong-Hua Liu  Can-Can Zhou  Jun Yu  Li-Jun Xiu  Zhong-Chun Sun  Hai-Tao Zhang 《应用地球物理》2017,14(1):10-20

Tight sandstone has a certain anisotropy. Using ultrasonic measurements of samples in three different directions and related matched experiments, this study systematically analyzes the pore structure and anisotropy of tight sandstone samples obtained from oil fields and compares results with those of shale. Results firstly show that the anisotropy of tight sandstone is mainly related to the compositional layering and thin interbedding which occur in different sedimentary environments. Tight sandstone has typical transverse isotropic medium characteristics, Young’s modulus increases in different directions with increasing confining pressure, Poisson’s ratio change is not obvious, anisotropic coefficients decrease with increasing effective pressure, and a certain linear relationship exists between ε, γ, and δ. This article finally summarizes anisotropy in different areas, thereby providing a foundation for the use of suitable appraisal models in different regions. This research can be used as an experimental reference for logging evaluation, seismic data interpretation, and fracturing develop of tight sandstones.  相似文献   

Analysis and application of the response characteristics of DLL and LWD resistivity in horizontal well     

Song Hu  Jun Li  Hong-Bo Guo  Chang-Xue Wang 《应用地球物理》2017,14(3):351-362

There exist different response characteristics in the resistivity measurements of dual laterolog (DLL) and logging while drilling (LWD) electromagnetic wave propagation logging in highly deviated and horizontal wells due to the difference in their measuring principles. In this study, we first use the integral equation method simulated the response characteristics of LWD resistivity and use the three dimensional finite element method (3D-FEM) simulated the response characteristics of DLL resistivity in horizontal wells, and then analyzed the response differences between the DLL and LWD resistivity. The comparative analysis indicated that the response differences may be caused by different factors such as differences in the angle of instrument inclination, anisotropy, formation interface, and mud intrusion. In the interface, the curves of the LWD resistivity become sharp with increases in the deviation while those of the DLL resistivity gradually become smooth. Both curves are affected by the anisotropy although the effect on DLL resistivity is lower than the LWD resistivity. These differences aid in providing a reasonable explanation in the horizontal well. However, this can also simultaneously lead to false results. At the end of the study, we explain the effects of the differences in the interpretation of the horizontal well based on the results and actual data analysis.  相似文献   

Investigation on the efficiency of a silicone antifouling coating in controlling the adhesion and germination of <Emphasis Type="Italic">Ulva prolifera</Emphasis> micro-propagules on rafts     

Jing Li  Lei Sun  ZhiMing Yu  XiuXian Song 《中国科学:地球科学(英文版)》2017,60(2):391-396

Prevention of annual “green tides” caused by blooms of the green macroalga Ulva prolifera, which have occurred in the Yellow Sea since 2007, has received much attention. Increasing evidence indicates that micro-propagules on the rafts used for Porphyra yezoensis aquaculture along the coastline of Jiangsu Province in China, were the primary source of these green tides. In this study, we investigated the effectiveness of a silicone antifouling coating for preventing the adhesion and germination of U. prolifera micro-propagules on bamboo and nylon ropes, which have been used in rafts for P. yezoensis aquaculture. Our results demonstrated that a coating of silicone (Sylgard 184) containing 1.0 wt.% sodium benzoate (NaB) could reduce the adhesion rate to <5% and completely inhibited the growth of U. prolifera propagules on the coated surfaces. Coating bamboo and nylon ropes with NaB-incorporated silicone thus proved a potentially effective method for controlling the initial biomass accumulation of U. prolifera.  相似文献   

Processes of initial collision and suturing between India and Asia   总被引：6，自引：0，他引：6  

Lin Ding  Satybaev Maksatbek  FuLong Cai  HouQi Wang  PeiPing Song  WeiQiang Ji  Qiang Xu  LiYun Zhang  Qasim Muhammad  Baral Upendra 《中国科学:地球科学(英文版)》2017,60(4):635-651

The initial collision between Indian and Asian continents marked the starting point for transformation of land-sea thermal contrast, uplift of the Tibet-Himalaya orogen, and climate change in Asia. In this paper, we review the published literatures from the past 30 years in order to draw consensus on the processes of initial collision and suturing that took place between the Indian and Asian plates. Following a comparison of the different methods that have been used to constrain the initial timing of collision, we propose that the tectono-sedimentary response in the peripheral foreland basin provides the most sensitive index of this event, and that paleomagnetism presents independent evidence as an alternative, reliable, and quantitative research method. In contrast to previous studies that have suggested collision between India and Asia started in Pakistan between ca. 55 Ma and 50 Ma and progressively closed eastwards, more recent researches have indicated that this major event first occurred in the center of the Yarlung Tsangpo suture zone (YTSZ) between ca. 65 Ma and 63 Ma and then spreading both eastwards and westwards. While continental collision is a complicated process, including the processes of deformation, sedimentation, metamorphism, and magmatism, different researchers have tended to define the nature of this event based on their own understanding, an intuitive bias that has meant that its initial timing has remained controversial for decades. Here, we recommend the use of reconstructions of each geological event within the orogenic evolution sequence as this will allow interpretation of collision timing on the basis of multidisciplinary methods.  相似文献   

Oxygen and hydrogen isotopic characterization of rainfall and throughfall in four South Korean cool temperate forests     

Mukesh Kumar Gautam  Yeon-Sik Bong  Byeong-Yeol Song  Jong-Sik Ryu 《水文科学杂志》2017,62(12):2025-2034

Understanding the isotopic composition of precipitation in a forested catchment is critical for ecohydrological studies. Changes in the water isotopes of rainfall were assessed during its passage through the canopy in throughfall, and the effect of different forest stands on the isotope composition of throughfall. In a cool temperate forest in Korea, rainfall and throughfall samples collected under Pinus densiflora (red pine), Castanea crenata (chestnut), Robinia pseudoacacia (black locust) and mixed stands (mix of these three species) were analysed for oxygen and hydrogen isotopes. Throughfall δ¹⁸O and δD were enriched compared to rainfall. A difference of δ¹⁸O and δD among throughfall may be related to the difference in interception–storage capacity of different species due to dissimilar canopy characteristics. Since isotopic composition of throughfall and rainfall are different due to canopy isotopic effects, use of rainfall isotopic signatures for ecohydrological studies in forested ecosystem can lead to biases.  相似文献   

松嫩地块东缘和佳木斯地块西缘电性结构   总被引：2，自引：0，他引：2       下载免费PDF全文

梁宏达  金胜  魏文博  高锐  侯贺晟  韩江涛  韩松  刘国兴 《地球物理学报》2017,60(4):1511-1520

横过松嫩地块东缘和佳木斯地块西缘的大地电磁测深剖面揭示了两块体结合带附近的深部电性结构.本文对剖面测点做了标准化数据处理,并对二维偏离度、构造走向进行了计算和分析,采用非线性共轭梯度(NLCG)二维反演方法对TM模式的数据进行了反演,获得了该剖面的地壳、上地幔电性结构模型,划分出三个典型构造单元:松嫩地块东缘、碰撞拼合带和佳木斯地块西缘.研究结果表明,研究区上地壳基本呈高阻特征,可能为岩浆岩,代表其经历了多期次岩浆作用,而松嫩地块东缘和佳木斯地块西缘的中下地壳的高导体可能与地幔物质的上涌有关;拼合带下方存在西倾的高导体和高阻体,可能是佳木斯地块向西俯冲到松嫩地块下方的构造遗迹;研究区可能发生了拆沉作用,与之伴随的地幔物质上涌可能是后期伸展作用的一个动力.  相似文献